Detecting the Norovirus Season in Sweden Using Search Engine Data – Meeting the Needs of Hospital Infection Control Teams

Norovirus outbreaks severely disrupt healthcare systems. We evaluated whether Websok, an internet-based surveillance system using search engine data, improved norovirus surveillance and response in Sweden. We compared Websok users' characteristics with the general population, cross-correlated weekly Websok searches with laboratory notifications between 2006 and 2013, compared the time Websok and laboratory data crossed the epidemic threshold and surveyed infection control teams about their perception and use of Websok. Users of Websok were not representative of the general population. Websok correlated with laboratory data (b = 0.88-0.89) and gave an earlier signal to the onset of the norovirus season compared with laboratory-based surveillance. 17/21 (81%) infection control teams answered the survey, of which 11 (65%) believed Websok could help with infection control plans. Websok is a low-resource, easily replicable system that detects the norovirus season as reliably as laboratory data, but earlier. Using Websok in routine surveillance can help infection control teams prepare for the yearly norovirus season.